Various known rear steering apparatuses each serving as a part of a four-wheel steering system of a vehicle are disclosed. For example, JP5098242B (i.e., hereinafter referred to as Patent reference 1) discloses a basic structure that includes a rod connected to rear wheels of a vehicle, a housing supporting the rod and fixed to a chassis of the vehicle, and a motor housed in the housing and actuating the rod for steering the rear wheels. There are various types of suspension mechanisms for supporting rear wheels of a vehicle and thus types of the rear wheel steering apparatus mounted to the suspension mechanism are varied. For example, JP2012-511465A (i.e., hereinafter referred to as Patent reference 2) discloses an apparatus that includes a blocking device for selectively transmitting a drive force from an electric motor to a push rod and the blocking device is supported by a module housing together with the electric motor and a transmission that is for converting a rotation of the electric motor to a translation of the push rod.
According to the known rear steering apparatuses disclosed in Patent reference 1 and Patent reference 2, it is difficult to downsize and to reduce the weight of the apparatus because the housing requires high intensity in order to absorb an axial force of the rod caused by a reaction force of tires and disturbances. Particularly, according to the construction of Patent reference 2, because the electric motor, the transmission, and the blocking device are supported by the module housing, the housing requires high intensity. Thus, it is difficult to downsize the apparatus.
A need thus exists for a rear steering apparatus for a vehicle which is not susceptible to the drawback mentioned above.